JP2006203783A - Radio communication equipment, base station device, mobile station device and radio communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To smoothly perform connection switching of radio communication. <P>SOLUTION: An accumulation amount control part 14 judges both of a link state with a mobile station 3 and an accumulation amount of a packet in a packet accumulation part 13, when a link with the base station 3 is established or when the accumulation amount of the packet is a fixed value as a judgment result, performs control for taking out the packets in an order of accumulation to the packet accumulation part 13. In addition, an output control part 12 transmits the packet taken out from the packet accumulation part 13 to the mobile station 3 via a radio transmitting part 11 on condition that the link with the mobile station 3 is established. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wireless communication apparatus and a wireless communication method for performing wireless communication by dividing digital data into packets.

Conventionally, the following systems are known as systems for performing wireless communication by dividing digital data into packets. That is, there is a system that performs wireless communication between a mobile station and a base station. In this system, a mobile station establishes a link (communication path) with a base station that is within a radio wave reachable range. Perform wireless communication. When the mobile station continues to move and the link between the mobile station and its base station is broken, the mobile station establishes a link with the next base station and transmits / receives a series of digital data. It comes to secure.
In this case, the mobile station is configured not to receive the same packet twice by switching the base station. Specifically, the mobile station records the number of received packets, and the base station before switching records the number of transmitted packets. Then, the base station after switching calculates the difference between the number of received packets at the mobile station and the number of transmitted packets at the base station, and transmits necessary packets to the mobile station. (For example, refer to Patent Document 1).
JP2003-283510 (paragraphs 0019-0023, FIG. 2)

  However, when a communication path trouble occurs between the mobile station and the base station, such as when a packet is lost due to noise or the like when a link is established between the mobile station and the base station. In the method described in Patent Document 1, the base station cannot accurately grasp the number of packets to be retransmitted to the mobile station, and the packet is transmitted to the mobile station before and after the base station is switched. It was a result.

  Therefore, the present invention has been made to solve the above-described problem, and an object of the present invention is to smoothly perform connection switching of wireless communication.

  In order to solve the above problems, the present invention provides a packet transmission unit that establishes a link with another wireless communication device and transmits a packet addressed to the other wireless communication device, and a packet storage unit that stores the packet And determining both the link state with the other wireless communication device in the packet transmission unit and the amount of packets stored in the packet storage unit, and as a result of the determination, a link with the other wireless communication device is established, or When the accumulation amount of the packet is a constant value, an accumulation amount control unit that performs control for taking out the packets from the packet accumulation unit in the accumulation order in the packet accumulation unit, and a packet extracted by the accumulation amount control unit, An output control unit that sequentially outputs to the packet transmission unit on the condition that a link with the other wireless communication device is established. It is use.

  According to the present invention, connection switching for wireless communication can be performed smoothly.

[Embodiment 1]
FIG. 1 is a block diagram showing a radio communication system according to Embodiment 1 of the present invention.
1, the wireless communication system includes a plurality of base stations (wireless communication devices) 1a, 1b, 1c, 1d, a packet processing device 2, and a mobile station (wireless communication device) 3. Examples of the mobile station 3 include railways and automobiles.
The base stations 1 a to 1 d are connected to the packet processing device 2 via the backbone network 4. The packet processing device 2 is for dividing the digital data and generating a packet addressed to the mobile station 3. Here, it is assumed that the packet processing device 2 is connected to a server device (such as a web server) via a network (not shown).
Each base station 1 a to 1 d has a communication area S. Within this communication area S, each base station 1 a to 1 d can establish a link with the mobile station 3. Hereinafter, the base stations 1a to 1d and the mobile station 3 will be described in order.

FIG. 2 is a block diagram showing an internal configuration of the base station. Here, the base station 1a will be described, but the other base stations 1b to 1d are the same.
In FIG. 2, a media conversion device (base station device) 100 is mounted on the base station 1a. The media conversion apparatus 100 includes a wireless transmission unit 11, an output control unit 12, a packet storage unit 13, a storage amount control unit 14, and a network interface unit (hereinafter simply referred to as “interface unit”) 15.

  The wireless transmission unit 11 includes a wireless antenna and the like, establishes a link with the mobile station 3, and transmits a packet addressed to the mobile station 3.

The interface unit 15 performs packet communication between the packet processing device 2 illustrated in FIG. 1 and the other base stations 1b to 1d. The interface unit 15 gives a serial number to the packet acquired by packet communication with the packet processing device 2. An example of this is shown in FIG. As shown in FIG. 3, a serial number 73 assigned by the interface unit 15 is added to a packet 70 including a packet header 72 in which packet destination information and transmission source information are described. Note that the position of the serial number 73 shown in FIG. 3 is not particularly restricted. For example, it may be added in the data field 74 or may be added immediately before the error detection field 75.
Returning to FIG. 2, the interface unit 15 further stores the packet 70 to which the serial number 73 shown in FIG. 3 is added in the packet storage unit 13.

  The packet accumulating unit 13 is a buffer, and here, a FIFO (First-In First-Out) method for extracting packets in the accumulation order is adopted. As a result, the most recently stored packet is retrieved last.

  The accumulated amount control unit 14 determines both the accumulated amount of packets in the packet accumulating unit 13 (hereinafter referred to as “FIFO accumulated amount”) and the radio link state with the mobile station 3 in the radio transmitting unit 11. Based on this, an output instruction (hereinafter referred to as “FIFO output instruction”) for extracting a packet from the packet storage unit 13 is performed. This transition of the operating state is shown in FIG.

  As shown in FIG. 4, when the power is turned on (Power On), the accumulation amount control unit 14 shifts from the power-off state S11 to the initialization S12. Thereafter, when the initialization is completed, first, the process proceeds to a state S13 in which the FIFO output instruction is stopped. At this time, the packet storage unit 13 sequentially stores the packets. Then, when the link with the mobile station 3 is established, or when the FIFO accumulation amount is a constant value (for example, the maximum value) ((1) in the figure), the process proceeds from S13 to S14. That is, the state shifts to a state in which a FIFO output instruction is output. At this time, the packet accumulating unit 13 sequentially extracts the packets and outputs them to the output control unit 12 described later. On the other hand, when the link is disconnected and the FIFO accumulation amount is less than a certain value ((2) in the figure), the process returns from S14 to S13.

  Returning to FIG. 2, the output control unit 12 outputs, to the radio transmission unit 11, the packet extracted by the control by the accumulation amount control unit 14 based on the radio link state with the mobile station 3 in the radio transmission unit 11. It has become. The transition of this operation state is shown in FIG.

  As shown in FIG. 5, when the power is turned on (Power On), the output control unit 12 also shifts from the power-off state S21 to the initialization S22. Thereafter, when the initialization is completed, the process proceeds to the discarding state S23. And when the link with the mobile station 3 is established (the figure (1)), it transfers to S24 from S23. That is, the state shifts to a state in which the packet is output to the wireless transmission unit 11. On the other hand, when the link is disconnected ((2) in the figure), the process returns from S24 to S23.

FIG. 6 is a block diagram showing the internal configuration of the mobile station.
In FIG. 6, the mobile station 3 includes a radio reception unit 31, a duplicate reception detection device 32, and a packet relay device 33. In the mobile station 3, the packet relay device 33 is arbitrarily connected to the data terminals 34a, 34b, 34c. The data terminals 34a to 34c are information terminals having a packet communication function. In the present embodiment, the radio reception unit 31, the duplicate reception detection device 32, and the packet relay device 33 are collectively referred to as a mobile station device.

The radio receiving unit 31 described above receives radio waves from the base stations 1 a to 1 d and outputs a packet addressed to the mobile station 3 to the duplicate reception detection device 32. Specifically, the packet addressed to the mobile station 3 means a packet addressed to the data terminals 34a to 34c.
The duplicate reception detection device 32 detects a serial number given to the packet and outputs a predetermined packet to the packet relay device 33.
The packet relay device 33 relays the packet output from the duplicate reception detection device 32 to the data terminals 34a to 34c.

Here, the processing procedure of the duplicate reception detection apparatus 32 will be described with reference to FIG.
First, the duplicate reception detecting device 32 resets a set of serial numbers assigned to a series of packets received in the past (this is called a received serial number set) (S31). Subsequently, when the duplicate reception detection device 32 receives a packet output from the wireless reception unit 31 (in the case of “Yes” in S32), the serial number of the received packet is a series of packets received after the reset in S31. It is confirmed whether or not it is included in the set of serial numbers assigned to, ie, the received serial number set for this time (S33).

  If the result of determination in S33 confirms that it is included in the reception sequence number set (in the case of “Yes” in S33), the duplicate reception detection device 32 discards the packet received in S32 (S34), Return to S32. This makes it possible to avoid duplicate transmission to the data terminals 34a to 34c.

  On the other hand, as a result of the determination in S33, when it is confirmed that it is not included in the reception sequence number set (in the case of “No” in S33), the duplicate reception detection device 32 reproduces the packet appropriately. The serial number is removed and the packet is relayed to the packet relay device 33 (S35). Then, the duplicate reception detection device 32 adds the serial number removed in S35 to the reception serial number value set for this time (S36), and then returns to S32. In this way, the data terminals 34a to 34c reproduce digital data by combining a series of packets.

Next, operation processing between each of the base stations 1a and 1b and the mobile station 3 will be described by taking as an example a case where the mobile station 3 switches the connection from the base station 1a to the base station 1b and performs wireless communication.
FIG. 8 is a timing chart showing an example of operation processing between each base station and mobile station. Here, after the packet processing device 2 transmits a packet addressed to the mobile station 3 to the base station 1a, the base station 1a transmits a packet in which the serial numbers "1" to "7" are assigned to the other base stations 1b to 1d. It will be described as broadcast transmission.

  First, in the base station 1a, when a link with the mobile station 3 is established as shown in FIG. 5B, serial numbers “1” to “3” are given until the time t1 when the link is disconnected. Packets are sequentially transmitted to the mobile station 3. After that, transmission of packets assigned serial numbers “4” to “7” is stopped. A symbol h12 represents a packet received with the link disconnected.

On the other hand, in the base station 1b, as shown in FIG. 5C, from the time t2 when the link with the mobile station 3 is established, packets to which the serial numbers after “3” are given to the mobile station 3. Sending. A symbol h11 represents a packet received in a state where the link is broken.
At this time, in the packet storage unit 13 of the base station 1b, the FIFO storage state is as shown in FIG. That is, after packets with serial numbers “1” and “2” are stored in the packet storage unit 13 and the storage amount reaches a certain value (maximum value), packets are taken out in order of storage from time t2. Packets to which new serial numbers after “3” are assigned are sequentially stored. This is because the following control is performed by the accumulation amount control unit 14 and the output control unit 12 of the base station 1b shown in FIGS.

  In the accumulation amount control unit 14, when a packet assigned with serial numbers “1” and “2” is stored in the packet accumulation unit 13, the accumulation amount becomes a constant value. Henceforth, a serial number “1” is assigned. Each packet is sequentially extracted from the output packet to the output control unit 12 (see FIG. 4A). Further, the output control unit 12 continues to discard the packet extracted by the accumulation amount control unit 14 until t2 when the link is established (see FIG. 5 (2)). After t2, the output control unit 12 causes the mobile station 3 to transmit the packet extracted by the accumulation amount control unit 14 via the wireless transmission unit 11. As a result of this transmission, the mobile station 3 receives the second packet with the serial numbers after “3” and “4” as shown in FIG.

  Note that the duplicate reception detection device 32 of the mobile station 3 discards the packet to which the second “3” is assigned by the process of S34 shown in FIG. As a result, the data terminals 34a to 34c of the mobile station 3 do not receive the packet with the serial number “3” repeatedly after switching from the base station 1a to the base station 1b, and the digital data is not received. Proper reproduction is possible. Therefore, connection switching of wireless communication can be performed smoothly.

FIG. 9 is a timing chart showing another example of operation processing between each base station and mobile station. Here, compared to the case of FIG. 8, the timing of switching from the base station 1a to the base station 1b is advanced, and the packet assigned with the first "3" serial number is lost and becomes an error packet. An example is shown.
In this case, in the base station 1b, as shown in FIG. 5C, from the time t2 when the link with the mobile station 3 is established, packets to which the serial numbers after “3” are assigned are sequentially transmitted to the mobile station 3. Sending.
At this time, the duplicate reception detecting device 32 of the mobile station 3 receives the packet with the second “3” serial number for the first time, so that the packet relay device 33 sends the packet without discarding the packet. Relay (see S31 to S35 in FIG. 7). The operations of the other base stations 1a and 1b and the mobile station 3 are substantially the same as in FIG.
As a result, the data terminals 34a to 34c of the mobile station 3 can receive a series of packets and appropriately reproduce digital data even when the packets are lost due to the timing of switching to the base station 1b.

[Embodiment 2]
FIG. 10 is a diagram illustrating a processing procedure of the duplicate reception detection apparatus in the mobile station according to Embodiment 2 of the present invention. The configuration of the wireless communication system including other base stations 1a to 1d is the same as that in the first embodiment. About the same part as Embodiment 1, the same code | symbol is attached | subjected and duplicate description is abbreviate | omitted.
In FIG. 7, when determining whether to discard or relay a packet in S33, attention is paid to whether or not the serial number of the packet received in S32 is included in the received serial number value set. The processing is focused on whether or not the serial number of the packet is larger than the serial number of the packet received in the past. Therefore, in FIG. 10, the following processing is different from that in FIG.

First, in S31A, the duplicate reception detection device 32 resets the maximum value (referred to as a serial number counter) of serial numbers of a series of packets received in the past.
In S33A, the duplicate reception detection device 32 determines whether the serial number of the received packet is equal to or smaller than the serial number counter.
In S36A, the duplicate reception detection device 32 changes the sequence number counter to the sequence number assigned to the packet received in S32. Even in this case, the duplicate reception detection device 32 can relay the appropriate packet to the packet relay device 33 as in the case of the first embodiment.

[Embodiment 3]
FIG. 11 is a block diagram showing an internal configuration of the mobile station according to Embodiment 3 of the present invention. In addition, the same part as Embodiment 1 attaches | subjects the same code | symbol, and abbreviate | omits duplication description.
The mobile station 3A in the third embodiment is greatly characterized in that a media conversion device 100A having a transmission / reception function is incorporated in place of the media conversion device 100 having a transmission function shown in FIG. Therefore, as shown in FIG. 11, the mobile station 3A includes a packet relay device 33A that outputs packets transmitted from the data terminals 34a to 34c to the media conversion device 100A. Other configurations are the same as those of the mobile station 3 shown in FIG.

As shown in FIG. 12, the media conversion apparatus 100A includes a wireless transmission / reception unit 11A and a data transmission / reception unit 15A. Other configurations are the same as those of the media conversion apparatus 100 shown in FIG.
The wireless transmission / reception unit 11A performs transmission / reception communication with the base stations 1a to 1d. Further, the wireless transmission / reception unit 11A outputs the packets received from the base stations 1a to 1d to the data transmission / reception unit 15A.
The data transmission / reception unit 15A outputs a packet to the duplicate reception detection device 32 or receives a packet output from the packet relay device 33A and outputs the packet to the wireless transmission / reception unit 11A.

  If comprised in this way, 3 A of mobile stations will be able to transmit a packet to the packet processing apparatus 2, switching the predetermined base stations 1a-1d by the function of the media converter 100A.

[Embodiment 4]
FIG. 13 is a block diagram showing a radio communication system according to Embodiment 4 of the present invention. In addition, the same part as Embodiment 1 attaches | subjects the same code | symbol, and abbreviate | omits duplication description.
In FIG. 13, two packet processing devices 2 that manage two base stations 1 a to 1 d at a time may be arranged in a distributed manner, and these packet processing devices 2 may be connected via an upper network 5. . The configuration of the wireless communication system including the other base stations 1a to 1d and the mobile station 3 is the same.
This is beneficial because it has the same operational effects as the first embodiment and can distribute the burden of packet processing.

[Embodiment 5]
FIG. 14 is a diagram showing an internal configuration of a mobile station including the media conversion device according to Embodiment 5 of the present invention. In addition, the same part as Embodiment 1, 3 attaches | subjects the same code | symbol, and abbreviate | omits duplication description.
14, the mobile station 3A includes a maximum accumulation amount setting unit 40 for changing a fixed value (for example, maximum value) of the FIFO accumulation amount with respect to the accumulation amount control unit 14 of the media conversion apparatus 100A illustrated in FIG. Furthermore, there is a feature in the point provided. With this configuration, it is possible to change the maximum value of the FIFO accumulation amount so that packet processing at the time of base station switching is properly performed according to the time required for the base station switching period K1 shown in FIG. It becomes.
The maximum FIFO storage amount can be defined as follows when the time required for the base station switching period K1 shown in FIG. 8 is T and the effective transmission rate of the transmitted packet is R bytes per second. Good. That is, the maximum FIFO storage amount B = R × T.

  The present invention is not limited to the embodiment described above. The configuration and processing procedure of the radio communication system including the base station and the mobile station may be configured by combining or changing the configurations of the first to fifth embodiments without departing from the spirit of the present invention. Also good. For example, the packet sequence number may be set by the packet processing device 2 instead of the base stations 1a to 1d.

1 is a block diagram showing a radio communication system according to Embodiment 1 of the present invention. It is a block diagram which shows the internal structure of the base station shown in FIG. It is a figure which shows the packet which added the serial number provided by the base station shown in FIG. It is a figure which shows the transition of the operation state of the accumulation | storage amount control part shown in FIG. It is a figure which shows the transition of the operation state of the output control part shown in FIG. FIG. 2 is a block diagram showing an internal configuration of the mobile station shown in FIG. 1. It is a figure which shows the operation | movement process of the duplicate reception detection apparatus of the mobile station shown in FIG. 3 is a timing chart illustrating an example of operation processing of the wireless communication system illustrated in FIG. 1. 12 is a timing chart illustrating another example of operation processing of the wireless communication system. It is a figure which shows the operation | movement process of the duplicate reception detection apparatus of the mobile station in Embodiment 2 of this invention. It is a block diagram which shows the internal structure of the mobile station in Embodiment 3 of this invention. It is a block diagram which shows the internal structure of the mobile station containing the media converter shown in FIG. It is a block diagram which shows the radio | wireless communications system which concerns on Embodiment 4 of this invention. It is a block diagram which shows the internal structure of the mobile station containing the maximum accumulation | storage amount setting part in Embodiment 5 of this invention.

Explanation of symbols

1a to 1d Base station 2 Packet processing device 3 Mobile station 11 Wireless transmission unit 12 Output control unit 13 Packet storage unit 14 Storage amount control unit

Claims (6)

  A packet transmission unit that establishes a link with another wireless communication device and transmits a packet addressed to the other wireless communication device, a packet storage unit that stores the packet, and another wireless communication in the packet transmission unit When both the link state with the device and the amount of packets stored in the packet storage unit are determined, and as a result of the determination, a link with the other wireless communication device is established, or the amount of packets stored is a constant value A link is established between the accumulation amount control unit that performs control for extracting the packets from the packet accumulation unit in the order of accumulation in the packet accumulation unit, and the packet extracted by the accumulation amount control unit with the other wireless communication device And an output control unit that sequentially outputs to the packet transmission unit on condition that the packet is transmitted.   The wireless communication apparatus according to claim 1, wherein the output control unit discards the packet extracted by the accumulation amount control unit when a link with the other wireless communication apparatus is not established.   The wireless communication apparatus according to claim 1, wherein a serial number is assigned to the packet.   A base station apparatus comprising the wireless communication apparatus according to any one of claims 1 to 3.   A mobile station apparatus comprising the wireless communication apparatus according to any one of claims 1 to 3. A wireless communication method in a wireless communication device that extracts and transmits a packet addressed to another wireless communication device from a packet storage unit,
Both the link state with the other wireless communication device and the amount of packets stored in the packet storage unit are determined. As a result of the determination, a link with the other wireless communication device is established, or the amount of packets stored is If it is a constant value, performing a control of taking out the packets from the packet storage unit in the order of storage in the packet storage unit;
Transmitting the packet extracted from the packet storage unit to the other wireless communication device on the condition that a link with the other wireless communication device is established. Communication method.

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